This invention pertains to an oxydehydrogenation process for preparing unsaturated aliphatic nitriles, such as acrylonitrile, fumaronitrile and maleonitrile.
Unsaturated aliphatic nitriles are useful comonomers in the formation of polymers having high heat and solvent resistance.
Certain catalysts are known for the oxydehydrogenation of saturated aliphatic nitriles to unsaturated aliphatic nitriles. U.S. Pat. No. 3,855,268 teaches the oxydehydrogenation of an alkylnitrile comprising forming a reaction mixture comprising the nitrile, an iodine-containing promoter, and oxygen, and passing the reaction mixture over a substantially inert material, such as carborundum, and then over a metal chromite catalyst. This process uses iodine, which must be separated from the products.
U.S. Pat. No. 3,965,141 teaches a process for the preparation of dialkyl aminoacrylonitrile by treating dimethylaminopropionitrile with a hydrogen acceptor in the presence of a dehydrogenation catalyst, such as Raney nickel, palladium or copper chromite. This process requires long reaction times and employs expensive hydrogen acceptors such as vinyl ethers and cyclic ethers.
U.S. Pat. No. 3,313,840 describes the catalytic oxydehydrogenation of succinic acid dinitrile to fumaronitrile and maleonitrile in the presence of at least one oxide of an element of Groups Vb and VIb of the Periodic Table. The preferred oxides are vanadium pentoxide, molybdenum trioxide, and particularly chromium (III) oxide. The dinitriles are produced in a constant ratio of fumaronitrile to maleonitrile of 5:4.
The above-identified processes are typically restricted to preparing narrow classes of nitrile products. Moreover, the known processes are costly, because they employ expensive metal catalysts, hydrogen acceptors, or promoters. Even more disadvantageously, the known processes are slow and inefficient. Accordingly, the known processes are not available for industrial adaptation.
It would be desirable to have a direct catalytic process for preparing an unsaturated aliphatic nitrile from a saturated aliphatic nitrile. It would be more desirable if such a process was capable of producing a wide range of unsaturated aliphatic nitrile products. It would be even more desirable if such a process produced essentially no by-products or waste stream. Finally, it would be highly advantageous if such a process was efficient, inexpensive and otherwise adaptable for industrial use.